package Demo91;


import java.util.LinkedList;
import java.util.Queue;

class Solution1 {
    int m, n;
    int[] dx = {0,0,1,-1};
    int[] dy = {1,-1,0,0};
    public int[][] updateMatrix(int[][] mat) {
        m = mat.length;  n = mat[0].length;
        Queue<int[]> q = new LinkedList<>();
        // 初始化
        int[][] dist = new int[m][n];
        for(int i = 0; i < m; i++)
            for(int j = 0; j < n; j++)
                dist[i][j] = -1;

        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if(mat[i][j] == 0) {
                    dist[i][j] = 0;
                    q.add(new int[] {i,j});
                }
            }
        }

        while(!q.isEmpty()) {
            int[] t = q.poll();
            int a = t[0], b = t[1];
            for(int i = 0; i < 4; i++) {
                int x = a + dx[i], y = b + dy[i];
                if(x >= 0 && x < m && y >= 0 && y < n && dist[x][y] == -1) {
                    dist[x][y] = dist[a][b] + 1;
                    q.add(new int[] {x,y});
                }
            }
        }

        return dist;
    }
}
class Demo {
    public static void main(String[] args) {
        Solution1 solution1 = new Solution1();
        int[][] dist = solution1.updateMatrix(new int[][]{{0, 0, 0}, {0, 1, 0}, {0, 0, 0}});

        for(int[] nums : dist) {
            for(int n : nums) {
                System.out.print(n + " ");
            }
            System.out.println();
        }
        System.out.println("ok");
    }
}